anemone Archives

September 25, 2025September 23, 2025

Hermit Crabs Stealing Homes

Hermit crabs might be accused of stealing their homes. Maybe “stealing” is a bit strong. Perhaps we should say they are “scavenging” or “recycling.” There are over 800 species of of these crabs, and most of them find an abandoned shell of a gastropod (snail) and move in.

The fact that hermit crabs (superfamily Paguroidea) live alone in shells is why we call them “hermits.” For a gastropod such as a snail, the shell is part of its body—an exoskeleton that offers protection. When the owner dies, the hermit takes over the abandoned shell. You might call it a mobile home because hermit crabs, like the original owners, carry the shells with them as they move.

Outside the shell, a hermit crab is vulnerable to predators because of its soft abdomen. Inside the shell, the crab is protected and can retract its entire body if needed. It has a curved abdomen to fit the shell, and the tip is designed to grip the shell tightly. Because they depend on shells for protection, sometimes two of them will fight over one they both like.

Marine hermit crabs spend most of their time underwater, breathing through gills. As long as their gills stay wet, they can stay on land briefly. There are about 15 species of land hermit crabs, but they still need access to water. People sometimes keep them as pets.

As a hermit crab grows, it needs larger shells, so they compete to find new homes. Some have observed them lining up in a queue from largest to smallest. When the largest moves to a bigger shell, each of the others moves up to the next size. Having shells available requires a balance between the number and size of the crabs and the gastropods that die. Sometimes, they are forced to find shelter in hollow pieces of wood or rock. Sadly, they may even take refuge in plastic trash from which they cannot escape.

Some larger hermit crabs support sea anemones on their shells. The venomous anemones protect the crabs from predators, and they benefit by eating food fragments that escape the crab’s grasp. Once again, we see how the web of life is designed to work together for survival. We believe this is no accident but the work of a Master Designer.

September 7, 2023September 5, 2023

Siphonophores – A Colony of Animals Living as One

The more science learns about the biological world, the more unique things we see. Most of us know about jellyfish, corals, and anemones. These ocean animals are members of the phylum Cnidaria. In that phylum, a strange order named Siphonophorae has 175 species. The Portuguese man o’ war is a member of the order of siphonophores.

Siphonophores may look like one organism, but they are actually colonies consisting of thousands of clones that function in different ways. Siphonophores start with a single “bud” called a zooid. The zooid replicates itself asexually, producing thousands of clones. Each clone has a specific job, such as eating, moving, or reproducing.

The colony of clones functions together as if they were one animal. For example, the Portuguese man o’ war has gas-filled zooids, allowing it to float on the ocean’s surface. Other zooids capture prey, while others digest the food. The individual zooids rely on each other for survival as one large functioning colony we call the Portuguese man o’ war.

In 2020, scientists found a siphonophore that was 150 feet long, probably the world’s longest animal. Most siphonophores live in the darkness of the deep oceans and are bioluminescent, using chemicals to produce light that attracts prey. The Portuguese man o’ war is an exception as a siphonophore that lives on the ocean’s surface.

The deep sea diving expeditions of the Schmidt Ocean Institute and the EV Nautilus have taught us much about the designs built into living things that allow life to exist in places totally alien to humans. Siphonophores make us realize that planet Earth is a wonderfully designed and unique place in the universe, full of amazing living creatures. We must treasure God’s gift and take care of it instead of abusing and polluting it.

Reference: Ocean Conservancy newsletter Splash for Fall 2023 page 2. You can learn more about the EV Nautilus HERE and the Schmidt Ocean Institute HERE.

July 27, 2020July 27, 2020

Anemones and Clownfish Symbiosis

There is an interesting relationship between anemones and clownfish. If you have had the joy of snorkeling in undeveloped areas, you may have had the unpleasant experience of bumping into one of some 800 species of anemones. Their tentacles contain toxin-filled capsules called nematocysts that fire stingers at anything that touches them. I can tell you from personal experience that it is extremely painful.

I finally learned to stay away from the anemones and just look at them. I saw that some fish died when they touched the tentacles. Interestingly, other fish, shrimp, and crabs lived among the tentacles and seemed unaffected by their stings. The very colorful clownfish lives right in the middle of the tentacles and appears to be immune to the anemone’s poison. Spider crabs and shrimp live at the base of the anemones. Crabs carry around baby anemones using them as defensive weapons. Even a baby anemone could deliver a nasty sting to my finger.

The clownfish seem to have the greatest skill for avoiding the anemone stings. When the clownfish is threatened, it will dive into the anemone tentacles for protection. The anemones eat algae remains that float in the water, and also small fish, sea urchins, shrimp, and some crabs. The clownfish benefit the anemones by removing parasites from them while the anemones provide the clownfish protection from predators.

So how do the clownfish avoid being stung by the anemones? They secrete a very thick mucus that does not trigger a response from the nematocysts. The clownfish can be all over the anemones and not get stung. Scientists are studying the mucus of the clownfish because it has potential uses for humans. The mucus is an anticoagulant and disrupts the gill function in sharks, making it an excellent shark repellent. Some researchers believe that the clownfish gets the mucus from the anemones, but other research studies show that the clownfish has a gene that produces the mucus. Research continues in the study of anemones and clownfish.

Science has a lot of data without a clear answer to how anemones and clownfish live in such a well-orchestrated symbiotic relationship. It would appear that the design of this symbiosis, like many others, is a product of God’s design and is not naturally acquired.

Data from National Wildlife magazine April/May 2020 and their websites.